Photometric determination of tetracycline based on surface plasmon resonance of silver nanoparticles

We report on a simple and sensitive method for the determination of tetracycline based on its reducing action on AgNO₃ in alkaline medium containing ammonia and sodium hydroxide at 65°C. As a result of this reaction, silver nanoparticles (AgNPs) are formed. The AgNPs are stabilized in solution by adding poly(vinyl pyrrolidone) as a capping agent. The formed AgNPs were identified by surface plasmon resonance absorption spectrum and transmission electron microscopy image. The plasmon absorption peak at 411 nm is proportional to the concentration of tetracycline. The calibration graph is linear in the concentration range of 0.05–5.0 mg/L with a detection limit of 0.013 mg/L. This method was applied to the determination of tetracycline in pharmaceutical products.     

Optimization of Linac-based neutron source for thermal neutron activation analysis

Journal of Radioanalytical and Nuclear Chemistry - A 20 MeV electron Linac based neutron beam has been shaped for neutron activation analysis (NAA) technique. A beam shaping assembly (BSA)...     

Epoxidation of alkenes with molecular oxygen and isobutyraldehyde catalyzed by immobilized vitamin B12 within Al-MCM-41

Vit-B₁₂/ Al-MCM-41 catalyzed successfully the epoxidation either of cis or trans — stilbene with O₂ as oxidant and isobutyraldehyde as co-reductant with 86–98% reactivity and 97–100% selectivity. Other olefins such as norbornene and styrene undergo epoxidation reaction under similar conditions with good to fair selectivity. Details of the reactions will be presented in this article.     

Metal ions exchanged montmorillonite as catalyst for alkylation of benzene with 1-dodecene

Summary About 8.5% of benzene was alkylated with 1-dodecene in the presence of Na⁺-montmorillonite. When the reaction was carried out with montmorillonite exchanged with Mn²⁺, Cu²⁺, Ni²⁺, Zn²⁺ and Fe²⁺ ions as catalyst (M²⁺/mont.), 91 to 95% of 1-dodecene was remarkably converted to a mixture of linear monoalkylbenzenes.     

A one-pot synthesis of piperidinium spirooxindoline-pyridineolates and indole-substituted pyridones in aqueous or ethanol medium

Molecular Diversity - Piperidinium spirooxindoline-pyridineolate has been prepared via one-pot multicomponent reaction of isatin, malononitrile, cyanoacetohydrazide, and piperidine in water or...     

Synthesis of functionalized 1,2,4-triazole-3-thiones from ammonium isothiocyanate,acid chlorides,and arylhydrazines

An efficient synthesis of 1-aryl-5-aryl(alkyl)-1,2-dihydro-3H-1,2,4-triazole-3-thiones via reaction between ammonium thiocyanate, acid chlorides, and arylhydrazines is described.     

Nanostructure Copper-exchanged ZSM-5 Catalytic Activity for Conversion of Volatile Organic Compounds (Toluene and Ethyl Acetate)

Gas phase catalytic oxidation of ethyl acetate and toluene was examined over copper modified ZSM‐5 catalysts under atmospheric pressure. Nanostructure of ZSM‐5 was characterized by XRD, SEM and TEM techniques. Elemental composition of ZSM‐5 was determined using EDX, ICP‐AES and XPS techniques. Results of catalytic studies showed better catalytic activity of Cu‐ZSM‐5 catalysts than those of parent ZSM‐5 and HZSM‐5, which revealed catalytic role of copper ions in the Cu‐ZSM‐5 catalysts. Effects of some parameters over catalytic conversion of these compounds were also studied. Ethyl acetate showed more reactivity than toluene over the Cu‐ZSM‐5 catalysts. Furthermore, the catalytic activity of Cu‐ZSM‐5 catalysts increased with increasing the copper loadings. The conversion behavior of a binary mixture of ethyl acetate and toluene was different from that of a single form. A promotive and inhibitive behavior was observed for conversion of ethyl acetate and toluene in the binary mixture, respectively. Water vapor as co‐feed had an inhibitive effect on conversion of organic compounds over the Cu‐ZSM‐5 catalysts.